Laboratoire de Physique Théorique
Toulouse - UMR 5152

How to "make" a spin liquid ?

What might have been a theoretical game a few years ago has become more and more an experimental reality. Indeed, spin-orbit coupling offers a broad diversity of anisotropic couplings. Changing the nature of the magnetic ion often leads to drastic modifications in the properties of the material, allowing for the exploration of a large region of parameter space. While on the other hand, changing non-magnetic ions may induce minute modifications of the model Hamiltonian, allowing for a fine-tuning of the crystal properties, which can then be coupled to external physical pressure. Rare-earth ions are fertile soils for such concepts, as illustrated by the pyrochlore family R2M2O7, and more recently by triangular (RMgGaO4 ...) and kagome (M2R3Sb3O14, R3Ru4Al12 ...) materials.

Motivated by these experimental possibilities, we will explore the physics of the fully anisotropic nearest-neighbour model on the kagome lattice, and show how it supports a unifying network of spin liquids with XXZ and Dzyaloshinskii–Moriya interactions [1]. This network revolves around the Ising antiferromagnet and terminates on classical chiral spin liquids. The Ising antiferromagnet is surrounded by an extended region of quantum disorder at linear order in spin wave theory. This region overlaps with the parameter region of Herbertsmithite ZnCu3(OH)6Cl2. As for the celebrated Heisenberg and XXZ antiferromagnets, they now belong to a triad of equivalent quantum spin liquids for spins S = 1/2. When the XXZ coupling becomes fully anisotropic, i.e. XYZ, another parameter dimension is added to this network, giving rise to unconventional (chiral) orders and new classical spin liquids [2]. If time allows, we will conclude this talk on the possibility to create kagome spin liquids by coupling topological charges via further neighbour interactions [3].

[1] Essafi, Benton & Jaubert, Nature Communications, 7, 10297 (2016)

[2] Essafi, Benton & Jaubert, in preparation

[3] Mizoguchi, Jaubert & Udagawa arXiv:1702.03794